Existing systems perform various types of energy conversion and energy storage. For example, some systems receive energy from one or more energy sources and store the received energy for future use. Other systems convert energy from DC (direct current) to AC (alternating current), typically via an inverter, or vice versa, typically via a transformer. Systems that receive energy from intermittent sources (e.g., solar cells or wind generators) need to make adjustments for changes in the amount of energy received. For example, solar cells temporarily provide a lower amount of energy when a cloud blocks light from the sun. In these systems, it is important to smooth out the temporary reductions in energy via an auxiliary power source.
Some systems that receive energy from multiple energy sources provide a separate inverter for each energy source. The use of multiple inverters increases the cost and complexity of such systems. Other systems provide inverters with multiple inputs to accommodate the multiple energy sources. These multiple-input inverters are more complex and expensive than single-input inverters.